Triumphrat

Sheepdog

My '03 790 is set up like your '01, more or less (I use a bellmouth and BellaCorse Teardrop mufflers). However, my bike starts instantly, warms quickly, has linear throttle response, and zero popping on decel. The difference is in jetting...I use a #125 main, #42 idle jet, and Thruxton needles w/no shims. I could probably go to a #122 main and improve my mileage a bit (42 mpg as is), but the bike runs so well I've been just as happy to leave well enough alone.

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2003 Bonneville T100 and 2007 Moto Guzzi California Vintage

luckyduck

Installed 42 pilot jets today. Mixture screws 2 turns. Still pops on decel.

Sheepdog

Check for leaks on the intake boots (I used HD SS clamps on mine...available from BellaCorse) and also at the diaphram. When adding or subtracting needle shims, it is possible to misalign the diaphram causing binding or even a tear. This would allow a vacuum leak that would cause popping, but be difficult to diagnose with the WD40 technique.

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2003 Bonneville T100 and 2007 Moto Guzzi California Vintage

alfacliff

you probably have already tried this, but did you check all the rubber vacuum caps? there are 4, betewen the carb and engine, used to check the ballance. a leaking or rotted one can cause a lot of potting and make it hard to start too.
cliff

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2006 Bonnie Black
1980 Yamaha xs650 sold 4-30-2011

denbow

Have you balanced the carbs ?

PieMan

Popping on the overrun can be quite hard to eradicate completely, going to 42 pilots is a good start. The next step is to check the header pipes at the cylinder head and at the joint to the silencers, any leak here will add to the popping. Going to 45 pilots may well get rid of the popping, but it will also make your bike way too rich in the bottom and mid ranges.

Before you go to the dyno, with your present setup you're running too rich, try 125 mains, with the 42 pilots and no shim. This will put you in the ball park and after your dyno you may have to change your jetting a small amount. Good luck.

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Mike (UK)

04 Bonnie Black Special

http://www.triumphtwinpower.com

luckyduck

As an update, I removed the snorkel, enlarged its opening and also removed the baffle.

I upped my jetting to:
-135 mains
-42 pilots
-1 shim under the stock needle

The problem I'm having is that the bike either runs very oddly. When I warm the bike up on startup, I have to put the choke nearly all the way in in order to ride away otherwise the throttle will bog when I crack it. And in the first few stoplights when I'm rev-matching my downshifts, if I have the choke more than halfway out the bike will bog and make a kind of a warbly gaspy sound.

2.5 turns out on the pilots lessens the popping but the bike feels rich and stumbles and hesitates at partial throttle around town. 1.5 turns feels better but the popping is constant.

Sheepdog

I put some idle mixture thumbscrews on my T100 when I switched to #42 idle jets. This allowed me to adjust "on the fly". Its also helpful when traveling to higher altitude.

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2003 Bonneville T100 and 2007 Moto Guzzi California Vintage

luckyduck

My harley idle screws are on their way.

Thanks!